Planar Cell Polarity (PCP) is required for proper orientation of a cell within a tissue and organ during development and regeneration. PCP has been described in adult neurons but its role during neuronal differentiation remains enigmatic. During postnatal cerebellum development granule neural precursors (GNPs) proliferate on the surface in the external granule layer, then start to migrate inward in a directed way to later form granule neurons (GN), the most abundant cell type in the brain. The differentiation process of GNPs is characterized by the highly conserved formation of three axons, the first two extending on opposite sides of the cell. Clusters of such axons are called parallel fibers, which thread through the Purkinje Neuron (PN) dendrites, forming synapses that each PN receives from more than 105 granule neurons. Defects in parallel fiber formation lead to reduced synaptic plasticity in the cerebellum, resulting in cognitive and behavior defects. Our study focuses on the role and effect of PCP in correct axon formation and orientation during early GNP differentiation. Through this study we aim to understand which mechanisms may contribute to proper neuronal development and orientation, leading to a more detailed insight of neuronal diseases and towards better treatments of these patients on a more global scale.